Surgical Tubing Connecting Shoes Helps Running More Than DARPA Soft Exoskeleton

A latex surgical tube, connecting shoes of running people, can improve running efficiency by 6.4%.

The tests were done exclusively with endurance running in mind. There were no tests of sprinters with their long strides and shorter race distances would derive benefits from this device. And, the running surface was consistently flat and level—so no trail running. There’s probably no discernable training effect; runners went back to their regular gait and efficiency when they removed the band.

Tens of Millions on Soft Exosuits

The US Military via DARPA has spent tens of millions of dollars developing soft exoskeletons to reduce the energy needed for walking and running.

DARPA funded soft exosuit development for over 5 years at Harvard’s Wyss Institute. A team of researchers at Harvard’s Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS), and the University of Nebraska Omaha now has developed a portable exosuit that assists with gait-specific hip extension during both walking and running. Their lightweight exosuit is made of textile components worn at the waist and thighs, and a mobile actuation system attached to the lower back which is controlled by an algorithm that can robustly detect the transition from walking to running and vice versa.

The team first showed that the exosuit worn by users in treadmill-based indoor tests, on average, reduced their metabolic costs of walking by 9.3% and of running by 4% compared to when they were walking and running without the device.

The rubber tubing connecting shoes is better at reducing the energy needed to run by 6.4% instead of only 4% for the soft exoskeleton. The device weighs 5kg in total with more than 90% of its weight located close to the body’s center of mass.

Rubber Tubing Connecting Shoes

Journal of Experimental Biology – Connecting the legs with a spring improves human running economy

Human running is inefficient. For every 10 calories burned, less than 1 is needed to maintain a constant forward velocity – the remaining energy is, in a sense, wasted. The majority of this wasted energy is expended to support the bodyweight and redirect the center of mass during the stance phase of gait. An order of magnitude less energy is expended to brake and accelerate the swinging leg. Accordingly, most devices designed to increase running efficiency have targeted the costlier stance phase of gait. An alternative approach is seen in nature: spring-like tissues in some animals and humans are believed to assist leg swing. While it has been assumed that such a spring simply offloads the muscles that swing the legs, thus saving energy, this mechanism has not been experimentally investigated. Here, we show that a spring, or ‘exotendon’, connecting the legs of a human reduces the energy required for running by 6.4±2.8%, and does so through a complex mechanism that produces savings beyond those associated with leg swing. The exotendon applies assistive forces to the swinging legs, increasing the energy optimal stride frequency. Runners then adopt this frequency, taking faster and shorter strides, and reduce the joint mechanical work to redirect their center of mass. Our study shows how a simple spring improves running economy through a complex interaction between the changing dynamics of the body and the adaptive strategies of the runner, highlighting the importance of considering each when designing systems that couple human and machine.

Video of the researchers talking about it. I rried embedding the video but it did not work.

SOURCES – DARPA, Journal of Experimental Biology
Written by Brian Wang, Nextbigfuture.com

15 thoughts on “Surgical Tubing Connecting Shoes Helps Running More Than DARPA Soft Exoskeleton”

  1. Wow, I totally forgot about it but I used to do that too. I wonder if that Enko spring shoe someone mentioned further up would support the movement.

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  2. They only tested it at the ankle. Some other location on the leg may be more effective, and less likely to trip up a soldier running on more rugged terrain. I suspect optimal is maybe 5 inches below the knee.

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  3. The video talk actually has illustrations, (Starting at about 33 minutes.) and, yes, they actually did run a piece of surgical tubing between the shoes, just above ground level.

    The hypothesized function is that it makes it energetically favorable to adopt a faster, shorter stride, by assisting the legs in returning towards each other, and because this results in the center of gravity moving up and down less, less energy is expended.

    A more complicated mechanism could produce the same forces, while not tripping you, but it would weigh more, too.

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  4. for sure. There is a whole movement getting started with spring-loaded shoes (see Enko running shoe for instance). They are considered performance-enhancing. But if you aren’t an elite racer you probably will get away with it. I presume Nike will one day make an Air Jordan that will allow you to dunk from the center line.

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  5. Article says “connecting shoes”, so initially I also assumed it was a direct connection, and wondered how would one even run with that at all? But consider that it doesn’t have to be direct. It could go up through a belt (maybe a roller on the belt?), and then back down. Or it might connect to the belt directly (then you’d have separate bands for each leg). Or some other design. Though my guess is still that this initial study was just a direct band on a treadmill.

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  6. use sci-hub.tw, enter the doi or title.
    The tubing is a dumb idea, for sure. Grunts can always use the tubing as slingshots. That will show the enemy who is in charge…

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  7. A lot of interesting science here, but a useless application. Basically you attach a rubber band between the middle inside of each shoe and run short with a short gait. The band pulls the leg from behind forward and expended energy to pull the band < energy needed to move the leg forward with the band.

    If I had springs under my shoe I would also use less energy than running without assistance….

    But you can’t use this for anything other than luring Home Shopping Network buyers. I can’t imagine any road racing association would allow this. That said, running very long distances is about upright stance and short gait, many steps. Saves energy.

    The Darpa suits are to make it easier to carry the ridiculously heavy loads (I was a jarhead and still have backaches) for endless hours.

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  8. To be fair, the rubber tube (why didn’t we get a photo of it?) would trip you up the moment you tried to actually use it in any military application. Unless you could convince the bad guys to only fight wars in places with nice smooth flat paved ground.

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  9. Skip run, I remember that as well, it seemed to be an effortless way to move faster, I wonder why I stopped doing it, all adults did.

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  10. Wheels are best. Then springs. I remember as a child I used to skip run. Adding springs to that would make it even better.

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  11. That’s got to be embarassing, when literally hobbling the runner with a rubber tube is more energy efficient than your expensive exoskeleton.

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